It isn't usual to use cars as pattern meassure of space resolution. However, as you see (or you
saw) in our Web site, we used very frequently terms such as "resolution 1mt", or
"resolution 30mts per pixel", for example. If you are a remote sensing expert or you understood this science,
you will understand the meaning of that term. However, if you don't understand the meaning of
that term, we say you that we are talking about the space resolution of a satellite sensor. What
is the space resolution?: it's the maximum pick up capacity of a sensor in terms of "size". In
other words, is "as far as a sensor can see". Which is the unit of the space resolution?: the
pixel. Because these terms can generate confusions in those people who still don't know remote
sensig details, we will exemplify these concepts in the more simpler and comprehensible
way. As we have already seen, a photo camera is a sensor. In this example we will use one aerial
photography to make different simulations of the pick up capacity of different the satellites.
And to see graphically we will use an object, a car, to appreciate the
differences. In this photo (taken from an aircraft from 1000mts of altitude) we see a car crossing a bridge
(first image to the left). In this first view, we see that the characteristics of this car can be appraised with
enough details. Considering this, we can deduce that this is a "sedan" model of approximately
4mts of length. On this basis, we calculated that the resolution by pixel of this car (and all
the image) it's aproximadeamente 20cm. In the second image, to the right, we have reduced this
resolution to 60cm per pixel (the resolution of the Quickbird satellite). Although the clearness
of details has disminished, still we could be appreciated clearly our car. More down, to the
left, we can see the same scene but with a resolution of 1mt (satellite Ikonos) Is this our
car?. Viewing it beforehand with greater clarity and added the fact of which it crosses a bridge, we
can affirm yes, this is the car. However, as it can be seen, its identification would be a little
difficult outside this context. As it can be appraised, at this scale begin to appear a small
squares grid. Each one of these squares is a pixel. Continuing, we have reduced the resolution to
10mts (Spot) satellite... and we say good bye to ous car. We don't believe necessary to show how
this scene would be seen at 30mts per pixel (satellite Landsat). Finally, between our simulation
and an original Ikonos image of a car rentals enterpise parking. As we can see, our
experiment comes near much to the reality.